Method and system for controlling an electrical system

Abstract

A method for reactivation of an electrical system of a vehicle comprising a first electrical system operating at a first lower voltage and a second electrical system operating at a second higher voltage, comprising: detecting a fault or a crash situation in the second electrical system; disconnecting a power source of the second electrical system; determining the fault of the second electrical system is no longer present or that the crash situation is resolved; reconnecting the power source to the second electrical system and increasing the voltage of the second electrical system from zero to an intermediate voltage lower than the second voltage; and if a detected current in the second electrical system is higher than a current threshold value; or if a detected voltage of the first electrical system is higher than a voltage threshold value; reducing the voltage of the second electrical system to zero.

The invention claimed is: 
     
       1. A method for reactivation of an electrical system of a vehicle comprising a first electrical system operating at a first voltage and a second electrical system operating at a second voltage, the second voltage being higher than the first voltage, the method comprising:
 detecting a fault in the second electrical system or detecting a crash situation; 
 disconnecting a power source of the second electrical system; 
 determining that the fault of the second electrical system is no longer present or that the crash situation is resolved; 
 reconnecting the power source to the second electrical system and increasing the voltage of the second electrical system from zero to an intermediate voltage lower than the second voltage; and 
 if a detected current in the second electrical system is higher than a current threshold value; or 
 if a detected voltage of the first electrical system is higher than a voltage threshold value; 
 reducing the voltage of the second electrical system to zero. 
 
     
     
       2. The method according to  claim 1 , wherein the voltage threshold value is the same as the first voltage. 
     
     
       3. The method according to  claim 1 , wherein the voltage threshold value is equal to a voltage safety limit of the first electrical system. 
     
     
       4. The method according to  claim 1 , wherein increasing the voltage to an intermediate voltage comprises ramping the voltage. 
     
     
       5. The method according to  claim 4 , wherein the ramp is a fixed ramp. 
     
     
       6. The method according to  claim 1 , further comprising, after the step of detecting a fault in the second electrical, disconnecting an electrical load from the second electrical system. 
     
     
       7. The method according to  claim 1 , further comprising, if a fault is detected, disconnecting loads from the second electrical system, and wherein the step of reconnecting comprises reconnecting the power source and if no fault is detected after increasing the voltage of the second electrical system, connecting an electrical load to the second electrical system. 
     
     
       8. The method according to  claim 1 , wherein the current threshold is set higher than an expected transient current resulting from reconnecting the power source. 
     
     
       9. The method according to  claim 1 , wherein the current threshold is set lower than an expected transient current resulting from reconnecting the power source, and wherein the method comprises filtering the current transient. 
     
     
       10. The method according to  claim 1 , wherein detecting a fault in the second electrical system comprises detecting a short circuit between the first electrical system and the second electrical system. 
     
     
       11. The method according to  claim 1 , wherein detecting a fault in the second electrical system comprises detecting a faulty component of any system and disconnecting the faulty component. 
     
     
       12. The method according to  claim 1 , wherein detecting a fault in the second electrical system comprises detecting a software error of the second electrical system. 
     
     
       13. A control system for a vehicle comprising a first electrical system operating at a first voltage and a second electrical system operating at a second voltage, the second voltage being higher than the first voltage, the control system comprising:
 a fault detection unit comprising a processor or programmable logic device that detects a fault in the second electrical system or to detect a crash situation; and 
 an electrical system control unit comprising a processor or programmable logic device that: 
 disconnects a power source of the second electrical system; 
 determines that the fault of the second electrical system is no longer present or that the crash situation is resolved; 
 reconnects the power source to the second electrical system and increasing the voltage of the second electrical system from zero to an intermediate voltage lower than the second voltage; and 
 if a detected current in the second electrical system is higher than a current threshold value; or 
 if a detected voltage of the first electrical system is higher than a voltage threshold value; 
 reduces the voltage of the second electrical system to zero. 
 
     
     
       14. The control system according to  claim 13 , wherein the electrical system control unit further reconnects the power source and, if no fault is detected after increasing the voltage of the second electrical system, connects an electrical load to the second electrical system. 
     
     
       15. The control system according to  claim 13 , wherein the voltage threshold value is the same as the first voltage. 
     
     
       16. The control system according to  claim 13 , wherein the voltage threshold value is equal to a voltage safety limit of the first electrical system. 
     
     
       17. The control system according to  claim 13 , wherein increasing the voltage to an intermediate voltage comprises ramping the voltage. 
     
     
       18. The control system according to  claim 17 , wherein the ramp is a fixed ramp. 
     
     
       19. A vehicle comprising a control system according to  claim 13 .